Originally Posted by mdisav (Post 2113539)

Anyway to eliminate the MAF entirely and have the car use the MAP? The fuel delivery is probably most determined by the MAP and TPS anyway

Originally Posted by mdisav (Post 2113539)

Super Job Evan! I look forward to the finished product.

Here is a question. Anyway to eliminate the MAF entirely and have the car use the MAP? The fuel delivery is probably most determined by the MAP and TPS anyway.

In the 80's the camaro and firebird tuned port injection systems first used a maf system and then used a map system only. There was also a kit to take the existing older maf system and convert it to the map system.

I figured if it was possible, you would be the man for the job Evan!

If the maf could be deleted somehow, bypassing the egr would probably go with the program. Or maybe there is a way to delete the maf and bypass the egr all in one configuration.

Do you think it is possible Evan?

Originally Posted by MB Paba (Post 2159180)

Evan,

Could you give a bit of info to help those of us with the '97 normally asperated engines figure this out? I was able to follow your instructions till I got to the part about the MAF pin 5. The EGR would no longer open but then it set a code for EGR flow. Guess it was looking for the response to the pressure drop. The 97 has a MAP sensor and an electrical connection on top of the EGR valve.

Also, I tried making a block off plate for the EGR but it sets a code. The U.S. version of the 97 has the electrical connector on top of the EGR so is not like the UK version.

Any help would be greatly apprectiated!! Let me know if you want a pic of the EGR or anything.

Thanks,
Louie

Originally Posted by MB Paba (Post 2162181)

The blcking plate did not work on mine. It still throws a code. I guess I can try the breather cap on the end of the tube but it makes me uneasy to think that you are sucking in air that is not filtered very well. Face it, an air cleaner element filters much more than some steel wool type stuff in one of those breather caps. Crankcase ventilation is a different animal.

With those concerns in mind, I was hoping tha Kar Tek could give a little guidance on how to figure out the '97s system so it could be eliminated like his turbo version was.

Originally Posted by KarTek (Post 2170915)

OK, I need to learn a little about the way your car operates. You'll need a mity-vac and a volt/ohm meter.

1. Put a 'T' in the line going to the EGR transducer and use the mity-vac to measure the vacuum with the engine running. You want to use a 'T' because you don't want to alter the EGR operation and set a code at this time. Note the vacuum level. 1.5" at idle. The vacuum went to 8" by just bumping the idle up slightly.

2. Shut off the engine and pull the 3 wire connector on the EGR valve. Use your volt/ohm meter set to ohms and measure the resistance for the following pin combinations:

1-2 3.170"
1-3 3.035"
2-3 1.914"

3. Finally, attach the mity-vac to the EGR line and pull the same amount of vacuum you noted in step one. Re-test the same three combinations of pins on the switch on the EGR.
1-2 3.170"
1-3 3.047 "
2-3 1.96"


Report all six values here.

Originally Posted by Jadavis (Post 2280613)

Wouldn't it be simpler to just disconnect the engine temperature input into the computer and install a dummy resistor to simulate 'cold engine'. That would stop the computer from telling the EGR to actuate.

What else is fed by the engine temperature sensor?

-Jim
(PS. I am asking because I have a W140 with the 603 engine. Your solution will not work for me and I am trying to find an easier fix for my engine.)

Originally Posted by hobbitss (Post 2281665)

Not sure about the older cars but I believe simulating a cold engine on the W210 and later models will cause the Engine Control Module to inject a richer than necessary mixture....
smoke........... :(

Originally Posted by Matt L (Post 2281668)

Rich mixture on a diesel? I don't think so.

Originally Posted by hobbitss (Post 2281677)

How about Richer mixture???

My 98 Idles cold at 0.3 gallons per hour
and
Idles warm at 0.1 gallon per hour...

Simulate a cold engine all of the time and that is more fuel going out the tail pipe... Correct???

Originally Posted by Matt L (Post 2281683)

At idle speeds, there is an excess of air in the cylinder which cannot and does not combine with any fuel. "Mixture" for a gasoline engine means just that, the actual constituents of the gas in the cylinder, but has no meaning for a diesel.

What you mean is "inject more fuel" which is also what happens when you press on the foot feed. So you can fool the computer -- with your foot.

More fuel means more power on a diesel, until you get to the point where you have insufficient air to burn. So more fuel means that you go faster. You will naturally back off with your right foot to compensate.

You do get an incomplete burn with a cold engine, but this is a completely different thing, and it is not correct that you can exploit it for more power. All you'll do is increase your idle RPM -- until the computer notices (that would be right away) and moves the rack just a bit.

Originally Posted by hobbitss (Post 2281782)

Ok, I understand all of that...
The computer also controls the volume of air available to the engine thru' actuation of the waste gate... Does it also limit air to a "cold" engine as it adds more fuel????

Originally Posted by Matt L (Post 2281843)

At idle, the computer cannot control the turbocharger because there is insufficient exhaust velocity.

The only reason to limit air to a diesel is to artificially create an intake vacuum to help with the EGR system. The NA 606 has a flap to do this, but the turbo does not. Thus, on the turbo model, the computer can only limit the air by not running the turbocharger, and at idle, the turbocharger really doesn't matter. It is just a slight restriction in the exhaust, and provides no boost.

At high speed, the turbocharger wastegate is actuated to control the impeller speed, mainly. More air never hurts a diesel; it's the injected fuel that moves you.

And no, the computer does not limit the air on a cold engine at idle. Yours takes more fuel at idle because that's how much fuel it takes to turn the engine over at idle speed. The engine idle speed is controlled exclusively through the rack position, which translates to gallons per hour. The air is not restricted. The rack modulator is, well, modulated to give you the proper idle speed. And when you press the pedal, the rack modulator is again, well, modulated to provide more fuel. Until you start providing substantially more fuel than is required at idle, which gives substantially more exhaust gas volume, you can have no boost.

Originally Posted by hobbitss (Post 2282384)

So, what exactly happens when you simulate a Cold Engine???

Originally Posted by KarTek (Post 2112102)

It's actually a pot. Here's the theory of operation of the EGR operation validation:

The EGR transducer is fed a unique 12v from the k40 relay - hot with ignition. (red/green wire in the picture) The transducer is connected to ECU pin 35 by another wire (green/gray). When the proper conditions are met, the ECU makes pin 35 low to activate the transducer and open the EGR valve.

When the EGR opens, there is a corresponding decrease in the flow of the intake air through the MAF sensor which is read as a voltage drop on the MAF signal feed to ECU pin 21. (yellow/white).

Problem 1: You can't just unplug the transducer because the ECU wants to see a load across the EGR transducer power feed and ECU pin 35 or a code will be set.

Problem 2: You can't just plug the vacuum line going to the EGR valve or plug the EGR feed tube because the ECU won't see the desired effect of the voltage decrease on pin 21 and again, you get a code.

So, to tackle problem 1, I first snipped the ECU pin 35 feed and then simply placed a 1/4 watt, 1k resistor inline between that and the EGR transducer power feed to simulate the load of the transducer. Now, that creates problem 2 because the EGR isn't opening and creating the MAF flow reduction.

To deal with problem 2, I needed to simulate the voltage reduction on ECU pin 21 on cue from ECU pin 35. Conveniently, when pin 35 goes low it makes a great place to shunt off some of the MAF signal voltage. I inserted a variable resistor there to make adjustments and find out exactly how much resistance was required in order to get the desired voltage drop. Now that the circuit has cleared all the codes, all I have to do is measure the resistance at the current setting and then swap in a fixed resistor in place of the variable one.

The reason for the diode is that you have two voltages going to the same pin (ECU 35): The <=12v from the transducer feed and the <=5v signal feed from the MAF. The diode keeps the higher voltage from spilling onto the MAF signal feed and altering it's value.

So that, in a nutshell is how it works.

Update - Here's a preliminary schematic:

http://i3.photobucket.com/albums/y71.../EGRDefeat.jpg

Originally Posted by KarTek (Post 2334096)

Hi, welcome to the group!

As you can see reading through this thread that the idea has been refined to pretty much the nth degree.

A few others along with me, are running one version or another of the electronic mod with success - myself for over a year now. The solution has been reduced to 3 components totaling less than a dollar (probably could be 2 components if you left the EGR modulator in place and capped the vacuum line.

I don't know how much simpler it could be... :)

I've ordered an occiliscope kit and I'll be using it to analyze the circuit to help develop an extension of this mod to remove the MAF as well.

Originally Posted by trapeze (Post 2339434)

I installed the EGR bypass today, as per Evan and Scott C.
I installed mine as Scott C did; using taps, !

Originally Posted by Olivier (Post 2339814)

Can you explain to me this? couldn't see any reference to it? :confused: Just curious to know if there is a different method.
Got mine like Evan's said, still working well :D
Thank you to the master :bounce:
Olivier

Originally Posted by Akraf (Post 2340512)

Could you write down what components i need to build this solution and som picture would be nice

thanks // Akraf

Originally Posted by trapeze (Post 2340685)

Olivier, I am referencing this whole thread. I suggest you read the whole thing.

The solution I used is from KarTek (Evan) Look at post #102 of this thread. I installed it like scott19_68, (Scott C) using taps instead of soldering it . Look at post #119 of this thread.

Originally Posted by Olivier (Post 2340701)

Hi Trapeze,
Thank you for this, I thought it was another way, I could not understand the "tap" thingy.
I didn't solder it either, I free a wee lengh of the wire from the isolation and wrapped the "mod" wire arounf the naked wire then tape it tightly.
All good and still going strong :)
Vroom vroom :D

Originally Posted by Olivier (Post 2340716)

The MAF I have is the one that came with the car, I guess its the original. There is a thread of someone trying to get rid of it, I would like this too, as if the MAF goes, its expensive...
Is the CDI engine MAF make any difference? Any part numbers on this?
I was going to remove all the EGR but I had a vision of me, sitting in a motionless car on the highway due to a limp mode trigger by the MAF as the EGR was not functioning properly as the MOD failed. For this I left the EGR there. If the MOD fail, I take it off and reconnect the vacuum pipe and off I go :)